In the manufacture of large medical X-ray detectors many challenges have to be overcome. In large medical X-ray detectors, materials with different thermal expansion coefficients (TCEs) need to be joined with an adhesive with a low modulus of elasticity to ensure the long-term reliability of the detector. Ultra-violet cured adhesives generally meet the requirements of low elastic modulus and low glass transition temperature. The use of a room-temperature process instead of the alternative, which is to use thermal curing, also limits the build up of mechanical stress and reduces manufacturing throughput time.
A substrate must be bonded onto a supporting frame by an adhesive layer, which is cured by the application of ultraviolet light. The supporting frame is typically in the form of a grid with openings between the grid members. The substrate is opaque to ultraviolet light, so the ultraviolet light has to be applied through openings in the frame. While the adhesive is exposed in the openings between the grid members, the latter mask the light creating a part of the adhesive layer that lies in the shadow of the grid members. As a result this part remains uncured at least only partly cured.